Embodiments of the present disclosure generally relate to air delivery systems, such as HVAC, air handling, heat pump, and energy exchange systems, and, more particularly, to control systems and methods for air delivery systems.
Enclosed structures, such as occupied buildings, factories and the like, generally include a heating/ventilation/air conditioning (HVAC) system for conditioning outdoor ventilated and/or recirculated air. The HVAC system typically includes a supply air flow path and an exhaust air flow path. The supply air flow path receives pre-conditioned air, for example outside air or outside air mixed with re-circulated air, or air from another source, and channels and distributes the pre-conditioned air into the enclosed structure. The pre-conditioned air is conditioned by the HVAC system to provide a desired temperature and humidity of supply air discharged into the enclosed structure. The exhaust air flow path discharges air back to the environment outside the structure. Without energy recovery, conditioning the supply air typically requires a significant amount of auxiliary energy, particularly in environments having extreme outside air conditions that are much different than the required supply air temperature and humidity. Accordingly, energy exchange or recovery systems are used to recover energy from the exhaust air flow path.
Conventional energy exchange systems may utilize energy recovery devices (for example, energy wheels and permeable plate exchangers) or heat exchange devices (for example, heat wheels, plate exchangers, heat-pipe exchangers and run-around heat exchangers) positioned in both the supply air flow path and the exhaust air flow path. Liquid-to-air membrane energy exchangers (LAMEEs) may be fluidly coupled so that a desiccant liquid flows between the LAMEEs in a run-around loop, similar to run-around heat exchangers that typically use aqueous glycol as a coupling fluid.
A liquid desiccant system is generally a direct contact system, in which the liquid desiccant removes moisture from the air it contacts. The temperature and humidity of the supply air that contacts the liquid desiccant may be modified by manipulating the temperature and concentration of the liquid desiccant. However, known desiccant-based HVAC energy exchange systems lack processes for conditioning the liquid desiccant to maintain supply air conditions.